Arch Linux

Sounds like an upstream issue, CMake should either provide their own *working* FindProtobuf module, or they should use the standard pkg-config files (but oh wait, cmake hates pkg-config and decided to reimplement it).

How should we install the cmake files? Currently we use the autotools build system to install protobuf...

Just copy that file to correct dir using install and sed the things in the in file you need to set?

If they're just using configure_file...

Have you considered submitting an upstream bug report asking them to install the file when using autotools as well?

"it needs protobuf-config.cmake to be installed for it to work"

This doesn't make sense. Cmake uses *either* FindFoo.cmake files provided by cmake (or one of its extensions such as ECM) *or* FooConfig.cmake files provided by the packages themselves, but not both. And FWIW, find_package(Protobuf) works fine here with the cmake-provided module.

I stumbled across this when trying to build a basic gRPC/protobuf example (https://github.com/faaxm/exmpl-cmake-grpc).
AFAIK one would need to adjust the protobuf PKGBUILD to also generate the protobuf-config.cmake from protobuf-config.cmake.in ?

[edit] I make a prototype PKGBUILD to build protobuf using CMake. Maybe this could serve as a template?
https://gist.github.com/jonathanschilling/b4aac25486b5bf47a4a1ff4daec94379

@arojas Unfortunately, not the case for protobuf, apparently:

-- Found Protobuf: /usr/lib/libprotobuf.so (found version "3.21.1")
CMake Error at CMakeLists.txt:58 (find_package):
Could not find a package configuration file provided by "protobuf" with any
of the following names:

protobufConfig.cmake
protobuf-config.cmake

Add the installation prefix of "protobuf" to CMAKE_PREFIX_PATH or set
"protobuf_DIR" to a directory containing one of the above files. If
"protobuf" provides a separate development package or SDK, be sure it has
been installed.

@m00n what are you trying to build? cmake is case-sensitive, it's find_package(Protobuf), not find_package(protobuf)

I wasn't the one to write the cmake file, but it does look like this works (It was `find_package(protobuf CONFIG REQUIRED)`, and i changed it to `find_package(Protobuf)`)